Backing sheet clamping device for printing cylinders



Jan. 21,1958 B. w. JOHNSON 2,820,409

BACKING SHEET CLAMPING DEVICE FOR PRINTING CYLINDERS Filed Sept. 2'. 1955 2 Sheets-Sheet '1 INVENTOR. BET/'IEL M (JOHNSOM BACKING SHEET CLAMPING DEVICE FOR PRINTING CYLINDERS Filed Sept. 2, 1955 Jan. 21, 1958' B. w. JOHNSON 2 Sheets-Sheet 2 EEE NWM

INVENTOR.

BETHEL 14/. da /v80 Arroe/v vs United States Patent-O BACKING SHEET CLAM'PING DEVICE FOR PRINTING CYLINDERS Ben t W- Jo nsq t pr inr M Applicationseptember l; 1 955, Serial No. ssazso n nrasle- 1. .1)

Thi rnt .n e a es: h d m ingdcv a r ast- 1 i bacnngshcets 1 mm wh h mmunt d b r, ie e printin or ugated and ol fiber shinn ng. EQ mi ers, oaths-P int n cy n ersotap in -shi P.

Presses of the type referred to above are used for printing upon; the panels. of corrugated or, solid fiber h pin semina s st r a emb v Q d. c nt n n, hsin s l farm. The in e of thessss a f 1: size, being, perhaps 6 tov 1 2 feet in length .0, in he mowe l s ri i rr ren v n Smalle cyl nd it a be d, a hwrt ut he iz antismsd typ ah in a cyrnder; used for the purpose stated, there is provided. a. wood covering, and. in use of the printing apparatus, a backing sheet, is, extended lengthwise of th cylinder, oyer. any desired portion of the circumce. to accornrnodate.thernhher dies. required for the p g job an d attachedtosaid backing sheet are the rubber i -sr towhich theprinting ink is applied, and whiehprint the desired-legends upon the box panels,

A. conventional practiceis to, staple, the backing sheet o h W9Qdov r ng o he pr nt. cyl nd after he rubber dies have been cementedv to the. surface of the back n h e a t e. e ir d 1 1 r.-v h op dge of, thebacking sheet is, first stapled to, the. wood. cylinder cover after. which the. backing, sheet is pulledfb y hand about. the circumference of; thecylinder until it has been drawnsnpglyand tightly aspossible against the. surface o a pdd Q F i'P r l e e...

hile e askinas eet, being he d t ghtl g n thesurface of the cylinder, the worker staples the. same ha esdsa e lm er s yg h a a'sh he a k: ns h et w th h Pr nting,di s rr iq rl ew d, her na mr as i n- It. has been found, in, this regard, that the eonrentional practice followed has seriousdisadvantages. In many instances, the. backing, sheet, though stapled: at its top andt o ed es a ll a at t n s. l n be h tightlyand tends tovibrate as. the cylinder rotates durn se Qt hear ntina app tu A or in l'y. it a been found. necessary in following. conventional practice, to. also, staple to: thesurface of, the.v wooden sleeve the edges of. the. rubher dies, These. are, stapled. at. their edges and. oftemat, their. nters alsn, whereyer there is uf fitisnt-tsnas b tween he. ines 91 l terin providing open dies. 5 191 141 9 die -t im, q re strar th ta le mus be the ha ki Sheri: imi ed li htly o he-de i qs t n ereof nd s p es npl dz on a ain. ith h s e at n bein repea d llfitil Pro re te v is made.

Afte the has Pr nt n -ma ha een made Staples must e, ul ed and r mov d t a the ba Sheet and sites, Excessi e. me n nlrssi n Operation, ,ad na disa van ge th min .8? W tends tqfiay a d Wea o t h cr es; o the baqkin'ashset Shouldthadis q lso tarlsihsrs "ice also. excessive expense results, since staples wear the die edges and cause them to lose shape.

Apart'frorn this, die wash, whichis used in washingthe printing ink from the dies, tendsto seep through theholes made. by thestaples. The result is that thecement that holds the dies to the backing sheetbecomes loosenedand further, the seepage causes. war-ping of thcbackingsheet.

Still further, the conventional practice. followedwears out the wood covering of the. cylinder dueto repeated applicationstof staples thereto in the same general. area of saidcylinder. This isespecially true ofthe center or midlength portion of the covering, where most backing sheetsof average size are stapled. Replacement ofthe woodcover requires, first, removalof theprinting. cylinder from the'rpress, for shipment of the cylinder to the factory where the press wasrbuilt. Therostof recoveringruns tomany hundreds of dollars, and in addition, the. box manufacturer must at all times keep avspare printingcylinder, also at great cost, to replace the cylinder that is being recovered. Even the operation of removing the cylinder-for the purposeofshipping the same requires, in some instances, the expenditure of a full days time, on the par-t', of two or three workmen. This results in lost production time, known as down.-timeforthe press, at substantial expense to the manufacturer.

The broad object of. the. present, inventionis. to provide a clamping device for the dieesupporting backing sheets, so designedas to permit mounting. of the backing sheets on the cylinder to becarried'out with marked facility and without the requirement of applying staplesthrough. the sheet and; the supportingdies. It will v be. appreciated that the clamping device will, as a result, permit. use of a single wood covering sleeve to extend over a far. greater time than has heretofore been the case, before the cylin- 'der needs to be recovered. The clamping device, further, preserves the dies used, prevents. seepage of die wash through the material ofthe. dies, and. extendsthc life of: the backingsheet itself.

A more specific object of. the present invention is to permit incorporation of a. backing sheet clamping device in a conventional printing cylinder of a press of the: kind referred to, with a minimum of modification or redesign.- ing, of the cylinder.

Other specific objects of the invention are to eliminate the necessity of maintaining spare printingcylinders; eliminate the cost of down time; eliminate the cost of stapling machines, staples and the laborainvolvedl in the stapling operation; assure a perfect register of thebacking sheet with the cylinder; assure the tightanchoring of the baclgingsheet to the cylinder surface, thus preventingvibration; eliminate the necessity of: remounting dies on new backing sheets; facilitate the. handling or storing. of rhounteddies by reason of the maintenance ofthe edges of the backingsheets. inv such manner that they will. at alltin esrema'in smooth and evenyeliminfite the danger of injury fgorn snagging or cutting of ones hands on accidentally overlooked staples; and permit the backing sheets to be made in sections, if so desired, one for each box panel to be printed, thus to permit any desired section to be moved for registering without disturbing adjacent sections.

Other objects and advantages will become apparent from a: consideration of the following description and the, appended claim in conjunction with the. accompanying drawings wherein:

Figure 1 is a fragmentary perspective viewv showing oneend of a printing cylinder equipped with a plurality of clamping devices formed according to the present in- Wniign;

,F' s.- 2'. s n pl d d a ra me tsrsrspsst ve 9 the ind an 9 s. o e am n dan e o an enla s df qalr;

Figure 3 is a fragmentary transverse sectional view, the scale being still further enlarged, taken substantially on line 3-3 of Figure 1;

Figure 4 is a transverse sectional view on line 4-4 of Figure l;

Figure 5 is a fragmentary longitudinal sectional view substantially on line 5-5 of Figure 4;

The reference numeral has been applied generally to a printing cylinder of the type used on a printer-slotter press, for imprinting selected legends on the panels of shipping containers of corrugated or solid fiber construction. A cylinder of this type includes an elongated core 12, to which is applied a wood covering or sleeve 14.

In accordance with the present invention, the sleeve is formed at angularly spaced intervals 16 about the cincumference of the same, with end to end channels 16. In the illustrated example, three such channels have been provided, but the number can be increased or decreased as desired, the number of channels being selected according to the circumference of the particular cylinder. In a commercial device, a cylinder used in an operation of the type referred to, having a relatively small diameter, would undoubtedly require no more than two clamping devices disposed diametrically opposite one another in the surface of the cylinder.

Secured within the respective channels are clamping assemblies generally designated as 18, and since these are all identical to one another, the description of one will suflice for all. Each clamping assembly includes a mounting strip 20, extending the full length of the cylinder, and having a channel shaped cross section. The strip is shown to particular advantage in Figure 2 and has the inner surfaces of its side walls diverging in a direction upwardly from the web of the strip, said inner surfaces being designated as 22 and terminating at their divergent edges at the top surface 24 of the mounting strip.

The top surface 24 is transversely curved to constitute a continuation of the circular cross sectional shape of the surface of the covering sleeve.

At the base of the side walls under-cut, longitudinal grooves 26 are formed, these extending the full length of the mounting strip. Further, medially between the opposite side walls of the mounting strip an upwardly projecting tongue 28 of T-shaped cross section is integrally formed upon the web of the strip and extends longitudinally and centrally of the strip from end to end thereof. At intervals along its length the tongue has openings receiving screws 30 whereby the mounting strip is fixedly secured to the covering sleeve and core, within the channel 16.

Supported within the mounting strip 20 are tightening bars 32, 34. In this connection, the tightening bars, though extending the full length of the cylinder and mounting strip, are formed in sections, with said sections abutting in end to end relation and cooperating to pro vide a tightening bar of full length. The purpose of forming the tightening bar in sections is to permit selected sections of the bar to be adjusted transversely of the mounting strip, without requiring an adjustment of the tightening bar over the full length thereof.

The outer side Walls of the respective tightening bars are inclined correspondingly to the surfaces 22 of the mounting strip, and at the base of said outer side walls, longitudinally extending, outwardly projecting lips 36, 38 are integrally formed on the bars 32, 34 respectively, and are engaged slidably within the under-cut grooves 26 of the mounting strip. The inner surfaces of the bars 32, 34 are formed with longitudinally extending grooves 40, 42 respectively, receiving the respective side portions of tongue 28. In this way the mounting bars are mounted to slide transversely of the mounting strip independently of one another and are guided in their transverse sliding movement by the tongue, lips and associated grooves, with the construction further serving as a hold-down means for the respective mounting bars.

The mounting bar sections have their inner side walls spaced apart as shown in Figure 5, and normally urging said sections outwardly from one another within the channel of the mounting strip are compression springs 44, seated in sockets provided at uniformly spaced intervals along the lengths of the bar sections.

Transverse threaded openings 46, 48 are formed in the several mounting bar sections, and engaged in said openings are screws 46, 48 respectively, the heads of which are disposed in the space between said sections. It will be seen, accordingly, that whenever it is desired to adjust any section away from the adjacent surface 22 of the mounting strip, it is merely necessary to extend an end wrench into the space between the bar sections, said wrench being applied successively to the several adjusting screws of the section that is to be moved outwardly. Rotation of said screws causes the associated section to be shifted outwardly from the adjacent side wall of the mounting strip against the restraint of the springs 44.

Overlying and coextensive in length with the respective tightening bars 32, 34 are clamping bars 50, 52. As shown in Figure 1, these are also sectionally constituted, extending in end-abutting relation. The clamping bars are, as shown in Figures 3 and 4, of approximately triangular cross section, having curved top surfaces constituting continuations of the curved surface of the wooded covering sleeve 14 and of the top surface 24 of the mounting strip. The respective clamping bars 50, 52, further, have vertical inner surfaces that lie in planes common to the vertical inner surfaces of the tightening bars, and are formed with transversely waved or corrugated undersides 54, 56 mating with complementarily formed top surfaces 58, 60 formed upon the respective tightening bars. As shown in Figures 3 and 4 the under surfaces of the clamping bars are inclined oppositely,

' transversely of the clamping device, and for the purpose of securing the clamping bars to the tightening bars, there are provided clamp screws 62, 64 having their heads seated in counterbored, smooth-walled openings formed in the top surfaces of the clamping bars, and threadedly engaged in sockets formed in the top surfaces of the tightening bars. The screws extend perpendicularly to the planes of the inclined top surfaces of the tightening bars, as shown in Figure 3, and circumposed about the shanks of the screws in the space between the tightening and clamping bars are coil springs 66, which exert a resilient, yielding pressure against the undersides of the clamping bars, tending to force the same upwardly out of engagement with the waved top surfaces of the tightening bars.

As previously noted herein, the respective tightening bars are each formed in sections, extending for substantially the full length of the cylinder, and the clamping bars are similarly formed. The mounting strip, however, is not so formed, and is a single piece of material the opposite ends of which are coterminous with the outer ends of the end sections of the clamping and tightening bars. Further, the respective clamping bar sections are each coextensive in length with the tightening bar section on which it is supported.

The opposite ends of the mounting strip and of the sectionally constituted clamping and tightening bars are disposed inwardly a short distance from the respective ends of the cylinder, and in the space between the cylinder ends and the ends of said bars and strips there are mounted end blocks 68, each of which is shaped complementarily to the cross sectional shape of the channel of the mounting strip, said end blocks fl'lllS having T-shaped bottom grooves and laterally, outwardly extending projections at their opposite sides as shown in Figure 1. The end blocks are fixedly secured in place by means of screws 70 or the .like, extending through openings .formed in the bottom -.of,tthe.r no nnting strip and engaged-1n .L'the sleeve of the cy in e .7 t

A baeking-sheefhas'been designated rat 72 .(Figures 3 and 4), and'is conventionallyformed as a multi-ply sheet of fibrous material, impregnated with synthetic rubber. .Gementedwn s i sheet, at ,selectedaloeations alongthe length of the cylinder, are rubber dies 74, having raised characters 76 to which the printing ink is applied, said rubber dies being adapted to imprint the selected legends upon the corrugated box panels.

By reason of the construction illustrated and described, the sheet can be of any desired length, and any desired number of dies can be secured thereto. Thus, the sheet may be disposed with its sides well inwardly from the ends of the cylinder, and may be engaged by any selected number of sections of the clamping and tightening bars. In mounting the sheet upon the cylinder, as a first step the clamping bar 52 may be loosened by backing off the screw 64 (Figure 3) to provide, as the associated springs 66 expand, a space between the clamping bar and the tightening bar 34, within which the end edge of the backing sheet is inserted. The screw 64 is then tightened, and this securely clamps said end edge of the backing sheet between the clamping bar 52 and tightening bar 34. The complementary, waved, sheet-engaging surfaces of the clamping and tightening bars secure the sheet against slippage from its assigned position, and in this regard, any particular cross sectional conformation of the sheet-contacting surfaces of the clamping and tightening bars can be provided, that will insure against said deviation of the backing sheet with respect to these bars. Thus, the mating surfaces of the clamping and tightening bars can be serrated, ribbed, or otherwise formed, it being mainly important that when the clamping bar is tightened against the tightening bar, the sheet 72 will not pull out of place, even though drawn tightly against the surface of the wood covering sleeve 14.

Then, the sheet 72 is extended about the selected portion of the cylinder circumference, with its other end edge to be engaged by a selected one of the remaining clamp devices. The sheet can thus extend between two adjacent clamping devices or alternatively, can be extended even further about the circumference of the device, crossing over one or more of the clamping devices, as desired. In the illustrated example in Figure 1, the sheet extends through 120 degrees of the circumference of the cylinder, with its opposite end edges engaged in the upper clamp device shown in Figure 1, and that clamp device shown at the right in Figure l. The sheet could even extend fully about the circumference of the cylinder, with both end edges thereof engaged in the same clamping device, with one end edge engaged between the clamping and tightening bars 52, 34 respectively, and the other engaged between the clamping and tightening bars 50, 32 respectively.

In any event, after the backing sheet has been pressed down snugly and evenly on the cylinder, and has been properly registered, the mentioned other end edge of the sheet is engaged between the clamping and tightening bars of the selected, second clamp device. This anchors both edges of the backing sheet.

As the next step, using an end wrench or similar tool, the tightening bolts 48, 46 of the selected clamping devices in which the sheet ends are anchored are turned slightly to shift the tightening bars outwardly from the adjacent side walls of the mounting strips. The bolts are turned slightly, one at a time until the desired tension has been imposed upon the backing sheet. Obviously, the tighteningbar at only one end of the sheet need be adjusted outwardly from the adjacent wall of the mountingstrip, in most instances, but if desired, the tightening bars in engagement with both ends of the backing sheet can be adjusted.

This pulls the backing sheet tight against the surface of the covering sleeve, .i'naking impossible-its working" loose. or becoming; subject "to a vibratory action. shun-1a the dies carried by the sheet need aslight ad ustments properly Jregis'fte'r thefsa'riie, -the selected clamping bar's can be loosened and the backing material moved slightly to the right or left, or upwardly'or downwardly as the case may be. v

As will be apparent, the entire "operation is carried out without the necessity of stapling eit her the backing sheet or the dies, and accordingly, the several undesirable characteristics of conventional practices are completely eliminated. Recovering of the cylinder is dispensed with wholly, thus not only saving the expense of recovering, but also saving on down time, the necessity of maintaining spare cylinders, etc. Apart from this, the life of the backing sheets is prolonged considerably, since fraying at the edges, tearing, etc. resulting from the repeated stapling thereof is eliminated completely. The same is true of the upper dies, and further, the tendency of die wash to loosen the bond between the rubber dies and the associated backing sheets is precluded, since the construction illustrated, by eliminating staples penetrating the rubber dies, prevents die wash from passing through the rubber dies to destroy the cementitious bond between the dies and backing sheet and warp said sheet.

A further important characteristic of the invention resides in the fact that it can be readily incorporated in wholly conventional cylinders of a printing apparatus of the type referred to previously herein. Since presses and cylinders of this type are quite expensive, a novel improvement in the method of attaching the backing sheets to the cylinders cannot be in any sense held to be commercially feasible, if it requires substantial modification and redesign of presses or of the cylinder components thereof, or the complete discarding of existing presses or cylinders.

The clamping device could be made a part of a new metal cylinder or a new wood covered cylinder such as would be incorporated in new presses, as well as applied to wood covered cylinders now in use.

It is believed apparent that the invention is not necessarily confined to the specific use or uses thereof described above, since it may be utilized for any purposes to which it may be suited. Nor is the invention to be necessarily limited to the specific construction illustrated and described, since such construction is only intended to be illustrative of the principles of operation, and the means presently devised to carry out said principles, it being considered that the invention comprehends any minor change in construction that may be permitted within the scope of the appended claim.

What is claimed as new is:

In a clamping device for a die-supporting backing sheet the combination, with a printing cylinder having a lon gitudinal recess, of: a channeled mounting strip fixedly mounted in said recess, said strip including a tongue extending longitudinally and centrally thereof at the bottom of said channel, the strip having the side walls of the channel undercut at the bottom of the channel to define guide grooves opening into the channel at opposite sides of said tongue; a pair of tightening bars extending in laterally spaced relation within said channel, said tightening bars having longitudinal grooves formed in one side thereof receiving said tongue, and including laterally, outwardly extending longitudinal ribs at their other sides slidably engaged in the respective guide grooves, for mounting the tightening bars in the channel for sliding adjustment independently of one another transversely of the strip and tightening bars, in the general direction of the circumference of the cylinder; and clamping bars overlying the respective tightening bars within said channel and connected to their associated tightening bars for adjustment approximately radially of the cylinder toward and away from the tightening bars, each of said clamping bars when adjusted toward the tightening bars co operating therewith in gripping a backing sheet therebetween, said tightening bars when'adjusted' circumferentially of thecylinder'being'respectively adapted to tension the gripped sheet against the cylinder surface.

" References Cited in the file of this patent UNITED STATES PATENTS 967,079 Stipe Aug. 9, 1910 8 Hohner Nov. 9, 1915 "Parmelee' Aug. 28, 1917 Pritchard et a1 Oct. 13, 1931 Huck May 25, 1943 FOREIGN PATENTS France Dec. 15, 1934 

